Attachment for a power saw to make plumb cuts

ABSTRACT

A level indicator attachment for a power hand tool to indicate the angle of inclination of the tool for making cuts at a predetermined angle. In a preferred embodiment, the level indicator comprises a circular bubble level adjustably positioned in a housing and frame mounted to the tool by use of preexisting fasteners used in assembly of the tool. Adjustment of the bubble level in the housing enables the level indicator to be calibrated or adjusted for different angle cuts. The invention is particularly suitable for use in cutting plumb cuts on rafter tails during construction of a building.

FIELD OF THE INVENTION

This invention relates generally to hand tools, and more particularly,relates to an attachment for a power saw to enable plumb or verticalcuts to be made without the necessity of first marking a vertical orplumb line.

BACKGROUND OF THE INVENTION

In the construction industry it is frequently necessary to make plumbcuts. For instance, during the construction of a building, carpentersand other persons working on the site measure and secure together piecesof dimension lumber to form a structure. During the course of measuringand assembling the lumber to form a structure, it may be necessary tomake angled cuts in the lumber, and a variety of measuring tools areavailable for appropriately marking the lumber which can then be cutalong the mark by using a power or hand saw.

In the construction of a roof, for example, boards are supported neartheir lower ends on the top edge of a wall and extend upwardly to aridge line where they are secured to like boards extending upwardly froman opposite wall. These boards serve as rafters in the roof structure ofa building. It is common practice in the prior art to install rafterswith the lower or tail ends cut perpendicular to the longitudinal axisof the rafter and after all of the rafters are installed to strike achalk line along a top or bottom edge of the rafters and then mark eachrafter by using an appropriate hand tool to provide a plumb or verticalline at the lower end of each rafter. A carpenter then uses a saw to cutalong the marked plumb lines to provide an appropriate angle on the tailends of the rafters. This procedure requires several time consumingsteps, adding to the cost of the project.

Similarly, it is frequently necessary to make angled cuts at the upperends or ridge line of the rafters or in other structures, includinghip-roof constructions and the like.

As presently practiced, all of these special cuts require carefulmeasuring and marking followed by cutting along the marked lines with anappropriate tool, such as a power hand saw.

Accordingly, there is need for a device which will enable angled cuts,and especially plumb cuts, to be made without first marking a line alongwhich the cut is to be made.

SUMMARY OF THE INVENTION

In accordance with the present invention, a simple and inexpensiveattachment is provided for a cutting tool, especially a power hand saw,which enables a vertical or other angled cut to be made without firstmarking a line along which the cut is to be made.

In a preferred embodiment, the attachment comprises a "bulls eye" orcircular level adjustably positioned in a mounting frame that isattachable to a power hand saw so that a carpenter or other person canobserve the position of the bubble in the level and make a plumb cut orother angled cut without first marking a line along which the cut is tobe made. Attachment of the frame of the level indicating device to thesaw is made by using existing bolts or screws on the saw, which areremoved and then repositioned through appropriate openings in the frameof the level indicating device.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing, as well as other objects and advantages of the invention,will become apparent from the following detailed description whenconsidered in conjunction with the accompanying drawings, wherein likereference characters designate like parts throughout the several views,and wherein:

FIG. 1 is a top, rear perspective view of a power saw having the levelindicating attachment of the invention affixed thereto.

FIG. 2 is a side view in elevation of a saw such as illustrated in FIG.1, with the level indicating attachment of the invention securedthereto.

FIG. 3 is a rear view in elevation of a saw such as illustrated in FIG.1, showing the level indicating attachment affixed thereto.

FIG. 4 is a rear perspective view of a saw such as illustrated in FIG.1, showing the locations of bolts or screws to which the levelindicating attachment of the invention may be secured.

FIG. 5 is an enlarged rear view in elevation of the level indicatingattachment of the invention.

FIG. 6 is an exploded perspective view of the level indicatingattachment of the invention.

FIG. 7 is a side view of the level indicating attachment, shownpartially in section.

FIG. 8 is a view illustrating how a saw may be oriented to cut a raftertail using the level indicating device of the invention.

FIG. 9 is a side view in elevation of the saw of FIG. 8, showing itbeing used to make a vertical cut in the tail end of a rafter.

FIG. 10 is a fragmentary schematic view in end elevation showing arafter and depicting how a plumb cut is made at the tail end of therafter to provide a vertical surface against which facia may beattached; and

FIG. 11 is a somewhat schematic perspective view showing a plurality ofrafters and how a chalk line may be struck to mark the point at whichvertical cuts may be made.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring more particularly to the drawings, a power hand saw having alevel indicating attachment according to the invention affixed theretois indicated generally at 10 in FIGS. 1-3, 8 and 9. A typical power handsaw without the level indicating attachment of the invention isindicated generally at 11 in FIG. 4. As specifically illustrated anddescribed herein, the power hand saw has a circular cutting blade 12.

The level indicating attachment of the invention is indicated generallyat 15, and comprises a mounting frame or bracket 16 having a cup-shapedhousing 17 with an end wall 18 at its base and an open other end 19. Acentral opening 20 is formed through the end wall 18.

A mounting ear 21 projects radially outwardly from one side of thecup-shaped housing 17 near its base end in essentially coplanerrelationship with the end wall 18, and a mounting arm 22 extends fromthe bottom of the cupped-shaped housing in generally coplanarrelationship with the ear 21 and includes an offset end portion 23.Mounting openings 24 and 25 are formed through the ear 21 and offsetportion 23, respectively. Although a particular relationship isillustrated herein between the mounting ear 21 and the arm 22, it shouldbe understood that variations in the positional relationships of theseelements can be made in order to mount the frame 16 to different saws ortools, depending upon the positioning and spacing of the bolts or screwsin the saw or other tool on which the level indicating attachment 15will be mounted.

A so-called "bulls eye" or circular level 30 is mounted in thecup-shaped housing 17 by means of a disc-shaped mounting plate 31 andbolt 32. The circular level 30 is first attached to the mounting plate31 as by use of an adhesive or other suitable fastening means, and thebolt 32 attached to the rear of the mounting plate 31 is then extendedthrough the opening 20 in the rear wall 18 of the cup-shaped housing 17.A lock washer 33 and nut 34 are placed on the bolt 32 on the side ofwall 18 opposite the position of the mounting plate 31 to securelyattach the mounting plate and thus the circular level 30 to the housingand frame 16. A transparent plastic cover 40 may be secured in the openend of the cup-shaped housing in covering relationship to the circularlevel 30 to protect it from dust, dirt and the like.

As seen best in FIG. 5, the face of the circular level is marked withsuitable indicia 36 positioned to correspond with different angle cutsthat may be made when the level indicating attachment is affixed to asaw 11. A bubble 37 is shown in full lines in FIG. 5 in the position itwould normally occupy during conventional use of the circular level,with the level horizontal, and is shown in dashed lines in the positionit would occupy when used in the manner contemplated by the presentinvention, applied to a saw 11 to make a vertical cut such as depictedin FIGS. 8 and 9.

As shown in FIG. 4, a typical saw 11 has structural components thatinclude fastening bolts or screws 50 and 51 in specific locations. Thelocations of these bolts or screws may vary depending upon theparticular make and model of a saw and a variety of differentlyconfigured attaching frames 16 may be provided to accommodate thosedifferent positions and spacings. The saw 11 shown in FIG. 4 has thebolts or screws 50 and 51 positioned appropriately for use with theframe 16 shown in FIGS. 3 and 5. Thus, the bolts or screws 50 and 51 aresimply removed and the frame 16 positioned against the back of the saw,with the holes 24 and 25 aligned with the holes in which the bolts orscrews 50 and 51 were originally received, and the bolts or screws thenrepositioned to securely fix the level indicating attachment of theinvention to the saw.

The level indicating attachment of the invention may be calibrated byclamping the saw in alignment with a known vertical or plumb line, or bysinking the saw blade into a known vertical or plumb line, and thenloosening the nut 34 so that the bolt 32 may be grasped with the fingersand rotated to rotate the mounting plate 31 and the circular level 30 toposition the bubble 37 in centered relationship with an appropriate mark36a. Thereafter, the nut 34 is tightened and the saw used to makevertical or plumb cuts, or other angled cuts as determined by the mark36 or 36a that is used on the face of the circular level 30.

Accordingly, and with particular reference to FIGS. 8-11, a chalk line Lmay be struck across the tail ends T of rafters R and the saw 11 used tomake plumb cuts C in the tail ends of the rafters without the need formarking vertical lines along which the cuts are to be made.

The frame and housing of the invention may be made of any suitablematerial, including 60-61 T-6 grade aluminum, and the circular level maycomprise any suitable model, such as the Sears Craftsman acryliccircular level, model number 39891.

While a particular embodiment of the invention have been illustrated anddescribed in detail herein, it should be understood that various changesand modifications may be made to the invention without departing fromthe spirit and intent of the invention as defined by the scope of theappended claims.

What is claimed is:
 1. A level indicating device for attachment to aconventional, unmodified power hand saw to enable the saw to be used tomake cuts at a predetermined angle relative to a vertical line withoutfirst having to mark a line along which the cut is to be made,comprising:a mounting frame having a cup-shaped housing with a centralaxis and at least one attaching arm having at least one openingtherethrough for receiving a fastener used in assembly of the saw, tohold the frame to the saw; and a circular bubble level carried by theframe in a position to be visible to a user of the power hand saw,whereby the level can be observed and by maintaining the bubble in apredetermined position the saw can be used to make a cut along a linehaving a predetermined angle relative to a vertical line without firsthaving to mark a line along which the cut is to be made, said circularbubble level being supported in said housing for adjustable rotationabout said central axis for calibration of the level, and having a facewith indicia thereon so that the level may be adjusted to differentrotational positions for cooperation of the bubble in the level withdifferent indicia for making different angle cuts.
 2. A level indicatingdevice as claimed in claim 1, wherein:the power hand saw has a handle ona rearward portion thereof, and a rotatable circular saw blade at oneside; and the frame is mounted to the saw so that the bubble level faceis in a vertical position when the saw blade is in a vertical position.3. A level indicating device as claimed in claim 1, wherein:the bubblelevel is attached to one side of a circular mounting plate that seats inthe cup-shaped housing, said mounting plate having a combined attachingand calibration bolt extending from the other side thereof, said boltbeing received in a central opening in the base of the cup-shapedhousing and having a free end exposed at a rear surface of thecup-shaped housing and a nut engaged on the free end of the bolt tosecure the mounting plate and the level to the housing.
 4. A levelindicating device as claimed in claim 3, wherein:the frame includes amounting ear projecting from one side of the cup-shaped housing at itsbase end, and a mounting arm projecting from another side of thecup-shaped housing, said mounting ear and mounting arm each having anopening therethrough to receive a fastener used to assemble the saw,whereby the frame can be mounted to the saw by existing fasteners usedin the assembly of the saw.
 5. A level indicating device as claimed inclaim 1, wherein:a transparent cover is received in the cup-shapedhousing in covering relationship to the bubble level to protect it fromdust and dirt and the like.
 6. A level indicating device as claimed inclaim 1, wherein:the cup-shaped housing comprises a cylindrical sidewall having a base end and an open end; and a mounting ear projects fromone side of the cup-shaped housing at its base end, and a mounting armprojects from another side of the cup-shaped housing at its base end,said mounting ear and mounting arm each having an opening therethroughto receive a fastener used to assemble the tool.
 7. A level indicatingdevice as claimed in claim 6, wherein:the mounting ear and mounting armextend in coplaner relationship with each other and with the base end ofthe cup-shaped housing.